Shigenori Hama

Formation of superionic crystals from mechanically milled Li2S–P2S5 glasses

A superionic crystal analogous to highly conductive thio-LISICON, which is a series of sulfide crystalline solid electrolytes such as Li4GeS4–Li3PS4, was successfully formed by the crystallization of mechanically milled Li2S–P2S5 glasses. The thio-LISICON phases have not been obtained by solid-phase reaction in the Li2S–P2S5 binary system so far, and this report is the first case of obtaining the thio-LISICON analogue in the binary system. The formation of this superionic crystal enhanced the conductivities of the glass, and the high ambient temperature conductivity of was achieved in the glass–ceramics derived from the Li-rich 80Li2S·20P2S5 (mol%) glass.

New lithium ion conducting glass-ceramics prepared from mechanochemical Li2S-P2S5 glasses

Amorphous solid electrolytes in the system Li 2 S-P 2 S 5 were prepared from a mixture of crystalline Li 2 S and P 2 S 5 using a mechanical milling technique at room temperature. In the composition range x≤87.5 of xLi 2 S(100-x)P 2 S 5 , conductivities of the glassy powders mechanically milled for 20 h were as high as 10 -4 S cm -1 at room temperature. The heat treatment of the 80Li 2 S.20P 2 S 5 glassy powders at around 220 °C produced dense glass-ceramics with high conductivity around 10 -3 S cm -1 at room temperature. The crystallization of conductive phases of Li 7 PS 6 , Li 3 PS 4 and unknown crystals from the glass matrix and the decrease of grain boundaries by the softening of the glassy powders are simultaneously achieved at relatively low temperatures, around 220 °C.

Fast Lithium-Ion Conducting Glass-Ceramics in the System Li2 S ­ SiS2 ­ P 2 S 5

Novel glass-ceramics solid electrolytes were prepared from mechanically milled glassy powders in the ternary system With an increase in the heat-treatment temperature, an ambient temperature conductivity of the obtained glass-ceramics reached which is higher than the maximum conductivity of the solid solutions in the system The enhancement on conductivity by heat-treatment over the crystallization temperature is due to the formation of the highly conductive crystalline phase with the same superlattice structure as the thio-LISICON phase of showing high conductivities over at room temperature.